Métalloprotéine

En biochimie, le terme métalloprotéine désigne une protéine qui comporte un ou plusieurs cofacteurs métalliques. Ces derniers sont des ions qui sont directement liés aux chaînes latérales des acides aminés de la protéine ou bien coordinés à un ligand non protéinique tel que la porphyrine des hémoprotéines. Environ la moitié des protéines connues possèdent un ou plusieurs sites de fixation d'ions métalliques afin d'assurer une fonction catalytique ou structurale. Les sites de fixation des ions métalliques peuvent être classés selon leur fonction en cinq grands groupes :

les sites catalytiques impliqués dans la fixation, l'activation de substrat ;
les sites impliqués dans le transfert d'électrons ;
les sites utilisés pour la fixation et le transport des molécules de dioxygène ;
les sites structuraux impliqués dans la configuration de la structure tertiaire et quaternaire des protéines ;
les sites impliqués dans la chélation métallique pour réguler la quantité de métal présent

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Publications associées (16)

Unraveling the Catalytic Pathway of Metalloenzyme Farnesyltransferase through QM/MM Computation

Matteo Dal Peraro

The protein farnesyltransferase (FTase) is a Zn2+-metalloenzyme that catalyzes the farnesylation reaction, i.e., the transfer of the 15-carbon atom farnesyl group from farnesyl diphosphate (FPP) to a specific cysteine of protein substrates. Oncogenic Ras proteins, which are among the FTase substrates, are observed in about 20−30% of human cancer cells. Thus, FTase represents a target for anticancer drug design. Herein, we present a classical force-field-based and quantum mechanics/molecular mechanics (QM/MM) computational study of the FTase reaction mechanism. Our findings offer a detailed picture of the FTase catalytic pathway, describing structural features and the energetics of its saddle points. A moderate dissociation of the diphosphate group from the FPP is observed during the nucleophilic attack of the zinc-bound thiolate. At the transition state, a resonance structure is observed, which indicates the formation of a metastable carbocation. However, no stable intermediate is found along the reaction pathway. Thus, the reaction occurs via an associative mechanism with dissociative character, in agreement with the mechanism proposed by Fierke et al. ( Biochemistry 2000, 39, 2593−2602 and Biochemistry 2003, 42, 9741−9748 ). Moreover, a fluorine-substituted FPP analogue (CF3-FPP) is used to investigate the inhibitory effect of fluorine, which in turn provides additional agreement with experimental data.

2009

Chargement

A genetic algorithm based design and experimental characterization of a highly thermostable metalloprotein

Esra Bozkurt, Nicholas John Browning, Marta Andreia Da Silva Perez, Rudolf Hovius, Ursula Röthlisberger

The development of thermostable and solvent-tolerant metalloproteins is a long-sought goal for many applica- tions in synthetic biology and biotechnology. In this work, we were able to engineer a highly thermo- and organic solvent- stable metallo variant of the B1 domain of protein G (GB1) with a tetrahedral zinc-binding site reminiscent of the one of thermolysin. Promising candidates were designed computationally by applying a protocol based on classical and first-princi- ples molecular dynamics simulations in combination with genetic algorithm (GA) optimization. The most promising of the computationally predicted mutants was expressed and structurally characterized and yielded a highly thermostable protein. The experimental results thus confirm the predictive power of the applied computational protein engineering approach for the de novo design of highly stable metalloproteins.

2018

Chargement

Multiscattering-enhanced optical biosensor: multiplexed, non-invasive and continuous measurements of cellular processes

Volodymyr Koman, Olivier Martin, Christian Santschi

The continuous measurement of uptake or release of biomarkers provides invaluable information for understanding and monitoring the metabolism of cells. In this work, a multiscattering-enhanced optical biosensor for the multiplexed, non-invasive, and continuous detection of hydrogen peroxide (H2O2), lactate and glucose is presented. The sensing scheme is based on optical monitoring of the oxidation state of the metalloprotein cytochrome c (cyt c). The analyte of interest is enzymatically converted into H2O2 leading to an oxidation of the cyt c. Contact microspotting is used to prepare nanoliter-sized sensing spots containing either pure cyt c, a mixture of cyt c with glucose oxidase (GOx) to detect glucose, or a mixture of cyt c with lactate oxidase (LOx) to detect lactate. The sensing spots are embedded in a multiscattering porous medium that enhances the optical signal. We achieve limits of detection down to 240 nM and 110 nM for lactate and glucose, respectively. A microfluidic embodiment enables multiplexed and crosstalk-free experiments on living organisms. As an example, we study the uptake of exogenously supplied glucose by the green algae Chlamydomonas reinhardtii and simultaneously monitor the stress-related generation of H2O2. This multifunctional detection scheme provides a powerful tool to study biochemical processes at cellular level.

Optical Soc Amer2015

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